Apparatus for controlling number of rotation of internal combustion engine

ABSTRACT

A apparatus for controlling the number of the rotation of an internal combustion engine, which is capable of feeding air-suction quantity back to the objective value and provided with memory storing and retaining the feedback value when the feedback operation is stopped. When faster adjustment is needed at the moment of resuming the feedback operation or performance characteristic of the air-suction control system largely varies during service period, the apparatus securely retains the feed-back value and applies it as the initial value to allow the engine to securely reactivate satisfactory startup operation.

FIELD OF THE INVENTION

The present invention relates to a apparatus for controlling the numberof the rotation of an internal combustion engine, which feeds the numberof non-loaded rotation of an internal combustion engine back to thepredetermined number of the rotation.

PRIOR ART

Conventionally, the number of non-loaded rotation of any internalcombustion engine has been controlled in order that it can be fed backto the predetermined number of the rotation. The object of controllingthe number of non-loaded rotation of the internal combustion engine isto set the number of non-loaded rotation for minimizing fuel consumptionduring non-loaded operation and also suppress variation of the number ofthe rotation caused by external disturbance. In either of these cases,it is essential that control be executed very quickly and precisely.

Roughly speaking, two main factors cause the number of the rotation ofany engine to vary, which can be classified into the primary factorcaused by variation of the loss of non-load of the engine itself or byvariation of thermal efficiency of the engine and the secondary factorcaused by either the variation of the adjustment gain present inairsuction adjusting means which adjusts the varied number of therotation caused by the primary factor or by variation of the atmosphericdensity substantially making up the supply source of fresh air.

To compensate for those variable factors, as proposed by the JapanesePatent Laid-Open No. 59-162340 (1984), there is a specific technique forcontrolling the number of the rotation of an internal combustion engine,which first generates the objective air-suction volume or the objectiveair-suction tube pressure in response to the adjustment signal inaccordance with the deviation between the objective value and the actualvalue of the number of the rotation of the internal combustion engine,followed by control of airsuction adjustment means in response to theadjustment signal in accordance with the deviation between the objectiveair-suction quantity or the objective air-suction tube pressure and theactual air-suction quantity or the actual airsuction tube pressure.

According to this prior art, since the adjustment signal (the signalwhich adjusts the number of the rotation of the internal combustionengine) is activated in accordance with the deviation between theobjective and actual values of the number of the rotation in conjunctionwith the primary factor of the variable rotations mentioned above andthe other adjustment signal (signal which adjusts air-suction quantity)is also activated in accordance with the objective and actual values ofthe air-suction quantity or the internal pressure of the air-suctiontube in conjunction with the secondary factor of the variable rotationsmentioned above, it is obvious clear that the variation of the rotationof the engine can precisely and quickly be adjusted rather than applyingfeedback control using only the number of the rotation.

Since those primary and secondary factors respectively renderconsiderable influence including substantial variation of characteristicduring a certain period of time, those adjustment signals extensivelyadjust the number of the rotation of the engine and the air-suctionquantity as well. This in turn obliges the control system to spend muchtime before allowing the adjustment signal to adjust the number of therotation from the initial value to the final value, thus eventuallyobstructing the initial object from properly controlling the number ofthe rotation of the engine being operated.

Furthermore, in an extreme case, the engine may not be activated at alldue to shortage of fresh air being supplied. If this occurs, improvementof the engine condition can not be expected because the operation of theengine rotation-number control starts.

The primary object of the present invention is to overcome thoseproblems mentioned above by providing a novel apparatus for controllingthe number of the rotation of an internal combustion engine, which canconstantly generate stable and satisfactory number of the rotation.

DISCLOSURE OF THE INVENTION

The apparatus for controlling the number of the rotation of an internalcombustion engine related to the invention provides means for retainingthe rotation-number adjustment signal and the air-suction adjustmentsignal even when stopping the control of the number of the rotation ofthe engine so that these signals can correctly reflect to the initialvalue when the system enters into the following operation forcontrolling the number of the rotation.

According to the invention, both the rotation-number adjustment signaland the air-suction adjustment signal are securely retained even whenthe control of the number of the rotation of the engine is stopped. Bothof these signals are used for making up the initial values when thesystem enters into the following operation for controlling the number ofthe rotation of the engine being activated.

The number of the rotation of the internal combustion engine is properlycontrolled so that it can be held at the objective value immediatelyafter the engine is activated or the operation for controlling thenumber of the rotation of the engine is resumed.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawing denotes the simplified block diagram of apreferred embodiment of the apparatus for controlling the number of therotation of an internal combustion engine related to the invention.

OPTIMUM CONSTITUTION FOR EMBODYING THE INVENTION

Referring now more particularly to the accompanying drawing, a preferredembodiment of the apparatus for controlling the number of the rotationof an internal combustion engine related to the invention is describedbelow. The accompanying drawing denotes the simplified block diagram ofa preferred embodiment of the apparatus related to the invention. Thereference numeral 1 denotes an internal combustion engine. The referencenumeral 2 denotes the air-suction tube which is internally provided withthrottle valve 3 for controlling the number of the engine rotation inresponse to load.

The air-suction tube 2 is provided with a pair of bypasses 91 and 92 inthe front and rear portions of the throttle valve 3. Air-section controlvalve 8 is provided between those bypasses 91 and 92. The air-suctionvalve 8 is comprised of either a linear solenoid valve or a DC-motorcontrol valve, while either of these is driven and controlled by thepower voltage outputted from the driving unit 7.

On the other hand, gear 41 which is interrelated to the rotation of theinternal combustion engine 1 is provided inside of this engine 1. Sensor42 detects the number of the rotation of gear 41 and outputs the enginerotation number signal n_(e) to differential amplifier 61.

The differential amplifier 61 also receives the objectiverotation-number signal n_(r) from the objective rotation-numbergenerator 5 which generates the objective rotation-number signal n_(r)indicating the objective non-loaded rotation number in response tovarious conditions of the engine and temperature for example.

The differential amplifier 61 computes error Δn between the objectiverotation-number n_(r) and the engine rotation-number signal n_(e) outputfrom the rotation-number sensor 42 and then outputs the error Δn to therotation-number adjuster 62.

On receipt of the error Δn, the rotation-number adjuster 62 generatesthe rotation-number adjusting signal in the direction of canceling theerror Δn by executing either proportional, integral, or differentialoperation before delivering the result to memory 12, which then outputsthe objective air-suction value QT relates to the engine 1 to the otherdifferential amplifier 111. The differential amplifier 111 also receivessignal Qe from the air-suction quantity sensor 10 which is providedinside of the air-suction tube 2 and detects the quantity of airabsorbed into the internal combustion engine 1 via the air-suction tube2.

In addition, the differential amplifier 111 outputs signal Qe receivedby the air-suction quantity sensor 10 and signals received by memory 12,i.e., the error ΔQ against the objective air-suction quantity QT, to theair-suction adjuster 112. On receipt of this error ΔQ, the air-suctionadjuster 112 generates the air-suction adjusting signal in the directionof canceling the error ΔQ by executing either proportional, integral, ordifferential operation before delivering the result to memory 13, whichthen outputs this signal to the driving unit 7.

Idle switch 141 is activated when the throttle valve 3 remains closed,i.e., when idling drive is underway. As soon as the idle switch 141becomes operative, the memory retention controller 142 allows thecontents of memories 12 and 13 to respectively be renewed, while thememory retention controller 142 constantly renews the adjustment signalsoutputted from the rotation-number adjuster 62 and the air-suctionadjuster 112.

Conversely, when the idler switch 141 remains inoperative, the memoryretention controller 142 inhibits memories 12 and 13 from renewing, sothat the memories 12 and 13 retains the adjustment signal in thecondition immediately before the idle switch 141 turns into theinoperative state.

Signal outputted from memory 13 is converted into electrical signals bythe driving unit 7. These electrical signals drive the air-suctioncontrol valve 8.

This valve operates itself so that it can remain open until gaining aspecific aperture area corresponding to the received electrical signal.Either a solenoid valve varying its position in proportion to the inputvoltage or a DC-motor valve varying its position in proportion to thepower-supplied duration can effectively be used for making up theair-suction control valve 8.

Certain quantity of air corresponding to the aperture area of theair-suction valve 8 flows through bypasses 91 and 92 to cause thequantity of air absorbed by the engine 1 to either increase or decrease.

In the manner mentioned above, the number of the rotation of theinternal combustion engine 1 is adjusted to the objective value, and atthe same time, the air-suction quantity is also adjusted to theobjective value. The air-suction adjustment signal minimizes the errorΔQ when those objective values are correctly adjusted.

this is because the air-suction adjustment signal properly adjusts theerror ΔQ which is present in various constituent factors such as unevenquantity of air leaked out of the throttle valve 3 at non-loadedposition or variation of the quantity of leaked air during a certainservice life, variation of performance characteristic due to error ortemperature caused by either the error of the initial characteristic orvaried characteristic after a long-term service of the air-suctioncontrol valve 8, or the dependency of the driving unit 7 on the powervoltage, or the dependency of gain on the atmospheric density, etc.

Next, the rotation-number adjusting signal adjusts the objectiveair-suction quantity QT by minimizing error Δn so that the number of therotation of the engine n_(e) can almost match the objective number ofthe rotation n_(r).

This is because the rotation-number adjusting signal properly adjustsvaried thermal efficiency caused by uneven loss or varied temperature inrespective parts of the engine 1 or variable load typically present inautomotive internal combustion engines normally generated by thosefittings such as lamps and motors for example.

Next, operation of the preferred embodiment shown in the accompanyingdrawing is described below.

When the idle switch 141 remains inoperative (i.e., when the engineitself is not in the idling state), memories 12 and 13 are respectivelyheld under retention, and thus, no operation is performed for adjustingthe number of the rotation of the engine 1. This causes the engine 1 toabide by the control of the throttle valve 3. When the idle switch 141is reactivated (i.e., when the engine 1 enters into the idlingcondition), the contents of memories 12 and 13 are delivered to therotation-number adjuster 62 and the air-suction adjuster 112 as theinitial value s for activating those adjusters so that the adjustmentsignal in the last idling condition can continuously be relayed.Consequently, adjusted condition becomes proper immediately afteractivating the idle switch 141.

When employing the system retaining the contents of memories 12 and 13while the engine stops after turning the control power source off, sincethe adjusted quantity immediately before stopping the engine reflectsitself when starting up the engine again, and in addition, since variousfactors which are variable through continuous service life such asclogging of air-suction control valve for example are preliminarilyadjusted, the engine can securely gain access to satisfactory startupperformances.

Anticipating that temperature at the moment of resuming the control ofthe number of the rotation may not always be equal to the last round ofthe control operation, if the adjustable quantity of the number of therotation and the adjustable quantity of air suction compensate for theerror caused by engine temperature and absorbed-air temperature, theapparatus related to the invention even allows part (for example by 50%)of memory content to reflect the initial value of the air-suctionadjuster 112 and the rotation-number adjuster 62 by delivering thesestored contents to those initial values of those adjusters 112 and 62.

The preferred embodiment shown in the accompanying drawing stores thosedata related to the adjustable quantity of the number of the rotation ofthe engine and the adjustable quantity of air suction in memories 12 and13. However, if the operative speed of adjusting the air-suctionquantity is so fast without requiring preliminary retention of theadjustable quantity, memory 12 may be deleted. Likewise, if there is noneed of extensively adjusting the number of the rotation of the engine,due to the same reason as above, memory 13 may also be deleted.

INDUSTRIAL APPLICABILITY

As is clear from the above description, the invention provides theapparatus with the engine-rotation number adjuster and the air-suctionadjuster by separating variable factors of rotation into the one whichis derived from the loss in the engine and the other from means foradjusting the air-suction quantity in order that these adjusters can beoperated during the idling cycle of the engine and stop their operationswhen the engine is not in the idling condition. Furthermore, since theapparatus related to the invention allows memory means to securelyretain date related to the adjustable quantity of air-suction quantityand the adjustable quantity of the number of the rotation of the engineduring the engine stops, the engine itself can instantaneously gainaccess to the properly-adjusted condition as soon as the control of thenumber of the rotation is reactivated. This in turn generates quitesatisfactory startup performance characteristic.

Consequently, the apparatus for controlling the number of the rotationof the internal combustion engine embodied by the invention providesunsurpassed effect when this control system is applied to any internalcombustion engine which generates a large amount of initial toleranceand variable performance characteristic during a long-term service life.

What is claimed is:
 1. An apparatus for controlling the number of therotation of an internal combustion engine comprising; a rotation-numberadjuster which generates an objective air-suction quantity and anobjective air-suction tube pressure of the engine in conjunction withthe number of the rotation and an objective number of the rotation ofthe engine; an air-suction adjuster which generates adjustment signalsin conjunction with the signal output from said rotation-number adjusterand the air-suction quantity and air-suction tube pressure of theengine; an air-suction control valve which increases and decreases oneof said air-suction quantity and air-suction tube pressure of the engineon receipt of a signal outputted from said air-suction adjuster; andmeans for retaining said air-suction quantity and the number of therotation of the engine by stopping at least one of those operationsexecuted by said rotation-number adjuster and said air-suction adjusterwhen the engine is not in idling condition.
 2. The apparatus forcontrolling the number of the rotation of an internal combustion engineas set forth in claim 1, wherein said rotation-number adjuster orair-suction adjuster is provided with constitution which allowsretention of adjustable quantity when operation of either of theseadjusters are stopped.